Priming explosive devices



M. PRECOUL June 24, 1969 PRIMING EXPLOSIVE DEVICES Filed March 2, 1965 1NVENTOR. M1 'cvfe/ Precau/ 3,451,339 PRIMING EXPLOSIVE DEVICES Michel Precoul, Paris, France, assignor to Societe Technique de Recherches Industrielles et Mechaniques, Paris, France, a French company Filed Mar. 2, 1965, Ser. No. 437,633 Claims priority, application France, Mar. 3, 1964,

Int. Cl. B421) 1/04, 1/02 US. Cl. 102-56 6 Claims Primings of projectiles by toroidal shock waves and in particular primings of hollow charges are known in themselves and they have been made the object of many forms of specific embodiment.

The present invention aims at a special form of priming through toroidal waves for a projectile having a hollow charge.

The description below concerns one such type of priming according to the invention. It is emphasized, however, that it is given merely as an example and is not intended as a limitation and that many other modes of construction, shapes, proportions, arrangements, etc. may equally well be used without departing from the framework of the invention.

The priming according to the invention is characterized essentially by an annular priming relay or booster preferably frusto-conical in shape placed in a seat made of an inert material, preferably a plastic, presenting notably, a low speed of transmission for shock waves.

The annexed drawing shows a view, partly in longitudinal section, of a hollow charge provided with the annular priming here concerned.

The charge comprises a casing 1, a facing 2 for the hollow charge and a principal body of explosive or main charge 3.

The rear closure for the charge is provided by a base 4 which carries a fuse 5. The fuse primer or detonator 6, constitutes the initiator of the pyrotechnic chain of the priming according to the invention.

In accordance with the invention, the annular priming or booster relay 7, preferably of frusto-conical shape, is positioned in a ring 8, of an inert material, having a cavity with a shape corresponding to the shape of the external surface of the booster 7.

An axial wedge 9 of an inert material, preferably conical in shape, fills, according to the invention, the interior space of the annular booster 7.

Thus the annular booster according to the invention, forms a complete block, substantially cylindrical in shape, positioned behind the principal explosive 3 of the hollow charge, with internal and external protection provided for the annular booster 7, itself, by the elements of inert material 8 and 9.

The pyrotechnic linkage between the primer of the fuse 5 and the annular block of priming or booster 7 according to the invention is provided by an intermediate relay element having in general a very flat shape, its diameter d being relatively very great in comparison to its thickness R.

The diameter d of the intermediate relay element 10 is equal to or a little larger at most, than the small rear diameter a" of the annular frusto-conical booster block 7, according to the invention.

Thus, these arrangements permit the continuous transmission of the detonation from the primer 6 to the booster block 7.

In accordance with the invention the large diameter D of the annular frustro-conical booster block 7 is relatively great and very near the diameter D of the principal explosive charge 3.

Thus in the system according to the invention the annular priming or booster block 7, preferably frusto-conical, assures the emission of toroidal waves of diameter T through the assembly just as f, f and j" which are propagated more rapidly through the intermediate relay element 10 and the annular frusto-conical booster block 7 than the axially directed waves g-g' retarded by their passage through the inert material of the axial wadge 9.

Conforming to the invention, the principal explosive charge 3 is terminated at its rear by a plane surface P, perpendicular to the longitudinal axis X-X' of the projectile, a plane which abuts and blends into the front surface of the annular frusto-conical block 7 according to the invention.

Similarly, the rear plane P of the annular frusto-conical booster block 7 according to the invention, is identical with the front face, likewise planar, of the intermediate relay element 10 (the relay being carried in a casing 10').

Finally, the rear face P", also planar, of the intermediate relay element 10, is substantially merged with or is very close to the front face of the primary primer 6 of the fuse 5.

Thus the system according to the invention, is characterized by a great simplicity in the organization of the pyrotechnic chain, constituted by the juxtaposition and coincidence of the planar surfaces perpendicular to the axis of the projectile, of the various elements making up said chain: the primary fuse primer, the intermediate relay element, the annular relay element or booster and the principal explosive charge.

Finally, the construction of the projectile may be in two sections. One section may comprise the body of the projectile 1 and the main or principal explosive charge 3 and the other section the rear base 4 containing the intermediate relay element 10, as well as the annular priming element or booster 7, wedged, protected and mounted by its system of elements of inert material 8 and 9.

The simple assembly, according to the invention, of the two sections completes a pyrotechnic chain having an annular primer or booster according to the invention which initiates the toroidal waves sought for.

The annular booster may be made of tetryl, the inert material may 'be made of Rilsan or an elastomer, and the principal explosive charge may 'be made of a mixture (6040) of hexogene (RDX) and ltolite (TNT).

The intermediate element 10 may be powder. The fuse primer 63 may be made of any of the various constructions and compositions well known to the art.

What is claimed is:

1. An explosive device having a casing, a principal explosive charge in said casing, said principal charge having a cavity with a lining to confer a hollow charge effect, fuse means, and a booster assembly positioned rearwardly of said principal charge, said assembly comprising a substantially cylindrical block of explosively inert material having a frusto-conic-al cavity, a conical plug of explosively inert material positioned in said frusto-conical cavity and smaller than said cavity, said plug and said block defining an annular chamber of frusto-conical shape having its larger end adjacent the principal charge, and a block of booster explosive in said chamber, the larger surface of said booster explosive block being in direct physical contact with the principal charge and the lesser surface being pyrotechnically connected with said fuse means.

2. The explosive device claimed in claim 1 in which the rear end of the principal charge and the forward end of the booster block are planar surfaces and are merged with one another, the outer diameter of the forward end 3 of the 'booster block being substantially equal to 'the diameter of the rear end of the principal charge.

3. The explosive device claimed in claim 1 and including a disc-like intermediate block of priming explosive having a thickness substantially less than its diameter, said intermediate block of priming explosive "being in contact with said booster block on one side and pyrotechnically connected to the fuse on the other.

4. The explosive device claimed in claim 3 wherein the intermediate block of priming explosive has a diameter substantially equal to the smaller diameter of the frus'toconical booster block.

5. The explosive device claimed in claim 3 wherein the intermediate block of priming explosive has a diameter slightly larger than the smaller diameter of the 'frustoconical booster block.

6. The explosive device claimed in claim 3 wherein the surface of the forward end of the intermediate block of priming explosive is merged With the surface of the rear end of the frusto-conical mass of booster explosive.

4 References Cited UNITED STATES PATENTS 2,809,585 10/1957 Moses l0256 2,843,041 7/1958 Stewart l0256 3,077,834 2/1963 Caldwell 102-24 3,100,445 8/1963 Poulter l0224 2,713,825 7/1955 Liljegren l0270 3,186,341 6/1965 Bjorklund et a1. 10286.5 3,238,872 3/1966 Zernow et a1. l0224 FOREIGN PATENTS 26,986 4/1954 Finland. 228,090 6/1963 Austria. 970,395 9/1964 Great Britain. 622,062 4/ 1949 Great Britain.

BENJAMIN A. BORCHELT, Primary Examiner.

JAMES FOX, Assistant Examiner.

U.S. Cl. X.R. 10224, 70 

1. AN EXPLOSIVE DEVICE HAVING A CASING, A PRINCIPAL EXPLOSIVE CHARGE IN SAID CASING, SAID PRINCIPAL CHARGE HAVING A CAVITY WITH A LINING TO CONFER A HOLLOW CHARGE EFFECT, FUSE MEANS, AND A BOOSTER ASSEMBLY POSITIONED REARWARDLY OF SAID PRINCIPAL CHARGE, SAID ASSEMBLY COMPRISING A SUBSTANTIALLY CYLINDRICAL BLOCK OF EXPLOSIVELY INERT MATERIAL HAVING A FRUSTO-CONICAL CAVITY, A CONICAL PLUG OF EXPLOSIVELY INERT MATERIAL POSITIONED IN SAID FRUSTO-CONICAL CAVITY AND SMALLER THAN SAID CAVITY, SAID PLUG AND SAID BLOCK DEFINING AN ANNULAR CHAMBER OF FRUSTO-CONICAL SHAPE HAVING ITS LARGER END ADJACENT THE PRINCIPAL CHARGE, AND A BLOCK OF BOOSTER EXPLOSIVE IN SAID CHAMBER, THE LARGER SURFACE OF SAID BOOSTER EXPLOSIVE BLOCK BEING IN DIRECT PHYSICAL CONTACT WITH THE PRINCIPAL CHARGE AND THE LESSER SURFACE BEING PYROTECHNICALLY CONNECTED WITH SAID FUSE MEANS. 